Optimization of submicron deep trench profiles with the STiGer cryoetching process: reduction of defects
| Autor: | Mohamed Boufnichel, Philippe Lefaucheux, Remi Dussart, Wassim Kafrouni, Thomas Tillocher, Pierre Ranson, Julien Ladroue |
|---|---|
| Přispěvatelé: | Groupe de recherches sur l'énergétique des milieux ionisés (GREMI), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), STMicroelectronics [Crolles] (ST-CROLLES) |
| Jazyk: | angličtina |
| Rok vydání: | 2011 |
| Předmět: |
Materials science
Passivation Silicon chemistry.chemical_element Nanotechnology 02 engineering and technology 01 natural sciences Ion Etching (microfabrication) [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph] 0103 physical sciences Electrical and Electronic Engineering 010302 applied physics business.industry Mechanical Engineering Plasma 021001 nanoscience & nanotechnology Electronic Optical and Magnetic Materials chemistry Mechanics of Materials Optoelectronics Undercut 0210 nano-technology business Layer (electronics) Critical dimension |
| Zdroj: | Journal of Micromechanics and Microengineering Journal of Micromechanics and Microengineering, IOP Publishing, 2011, 21, pp.085005. ⟨10.1088/0960-1317/21/8/085005⟩ |
| ISSN: | 0960-1317 1361-6439 |
| DOI: | 10.1088/0960-1317/21/8/085005⟩ |
| Popis: | International audience; The STiGer process is a time-multiplexed cryogenic etching method designed to achieve high aspect ratio structures on silicon. SF6 or SF6/O2 plasmas are used as etch cycles and SiF4/O2 plasmas are used as passivation cycles. Trenches with a critical dimension of 0.8 μm have been etched to a depth of 38 μm with an average etch rate of 1.8 μmmin−1. These features exhibit both undercut and a defect which is called extended scalloping. We describe this defect specific to the STiGer process and we discuss its origin: the extended scalloping is composed of anisotropic cavities developed on the sidewalls of the feature top (typically in the first 2-3 μm below the mask). It originates from ions scattered at the feature entrance that hit the top profile and remove the passivation layer where it is weakest. Then, we propose two methods to reduce this extended scalloping. The first consists in adding a low oxygen flow in the etching cycle. It favors a low additional passivation which reduces scalloping. The second technique consists in gradually increasing the SF6 flow from a low value to the nominal value. Consequently, the process starts with a low etch rate and an efficient passivation. |
| Databáze: | OpenAIRE |
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